Discovery of the slowest X-ray pulsar in the SMC, AX J0049.5-7323, with ASCA

The discovery of coherent pulsations with ASCA from an X-ray source, AX J00 49.5-7323, is reported. The barycentric period was determined to be 755.5 /- 0.6 s, which is the longest among X-ray pulsators in the SMC. The X-ray spectrum has been found to be unchanged through ASCA observations, with a p hoton index of similar to 0.8 and a luminosity of similar to 5 x 10(35) erg s(-1) (0.7-10 keV). Archival data of the Einstein and the ROSAT satellites indicate that the flux has been less than or similar to 10(-12) erg s(-1) cm(-2) (less than or similar to 5 x 10(35) erg s(-1)) for over 20 years and exhibits a variability with a factor of greater than or similar to 10. We argue that AX J0049.5-7323 is an X-ray pulsar with a Be star companion.